Comparison of the effects of ionizing radiation at twelve dose rates from 0.0015 to 100 rad(Si)/s
Evidence is presented that two competing failure mechanisms exist in the Si-SiO2 system, with one mechanism dominating at low dose rates and the other at high. Much lower dose failures than expected were discovered at low dose rates (less than 0.1 rad(Si)/s) and very low dose rates (about 0.001 rad(Si)/s) in commercial SGS 4007 CMOS devices. These failure doses plotted versus dose rate have a bell-shaped curve, rather than the expected straight line (decreasing with increasing dose rate), indicating that a different failure mechanism is dominant at low dose rates than at high.